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A Large Ion Collider Experiment

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LS2 installation: TPC

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ITS Outer Barrel

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LS2 Installations: ITS Outer Barrel and MFT

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LS2 Installation: FIT

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Heavy-ion collision

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proton-proton collision

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ALICE INDICO

update on - 05:21:45

ALICE Calendar

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ALICE mission

ALICE is optimized to study the collisions of nuclei at the ultra-relativistic energies provided by the LHC. The aim is to study the physics of strongly interacting matter at the highest energy densities reached so far in the laboratory. In such conditions, an extreme phase of matter - called the quark-gluon plasma - is formed. Our universe is thought to have been in such a primordial state for the first few millionths of a second after the Big Bang, before quarks and gluons were bound together to form protons and neutrons. Recreating this primordial state of matter in the laboratory and understanding how it evolves will allow us to shed light on questions about how matter is organized and the mechanisms that confine quarks and gluons. For this purpose, we are carrying out a comprehensive study of the hadrons, electrons, muons, and photons produced in the collisions of heavy nuclei (208Pb). ALICE is also studying proton-proton and proton-nucleus collisions both as a comparison with nucleus-nucleus collisions and in their own right. In 2021, ALICE completed a significant upgrade of its detectors to further enhance its capabilities and continue its scientific journey at the LHC in Run 3 and 4, until the end of 2032. At the same time,  upgrade plans are being made for ALICE 3, the next-generation experiment for LHC Runs 5 and 6.

Recent highlights

 

Recent highlights

ALICE Review Paper - now published in EPJC

Review paper
The ALICE experiment: a journey through QCD: Read more

ALICE does the double-slit

double slit
Using collisions between lead nuclei at the LHC, the ALICE collaboration has measured an interference pattern akin to that of the famous double-slit experiment: Read more

ALICE in ICHEP 2024

ALICE at ICHEP 2024
ICHEP 2024 (18 - 24 July), Prauge. ALICE has a major presence in the Conference: Read more
See all highlights

Latest ALICE Submissions

Multiplicity-dependent jet modification from di-hadron correlations in pp collisions at $\sqrt{s} = 13$ TeV Short-range correlations between charged particles are studied via two-particle angular correlations in pp collisions at $\sqrt{s}=13$ TeV. The correlation functions are measured as a function of the relative azimuthal angle $\Delta\varphi$ and the pseudorapidity separation $\Delta\eta$ for pairs of primary charged particles within the pseudorapidity interval $|\eta| < ~ 0.9$ and the transverse-momentum range $1 < ~ p_{\rm T} < ~ 8$ GeV/$c$. Near-side ($|\Delta\varphi| < ~1.3$) peak widths are extracted from a generalised Gaussian fitted over the correlations in full pseudorapidity separation ($|\Delta\eta| < ~1.8$), while the per-trigger associated near-side yields are extracted for the short-range correlations ($|\Delta\eta| < ~1.3$). Both are evaluated as a function of charged-particle multiplicity obtained by two different event activity estimators. The width of the near-side peak decreases with increasing multiplicity, and this trend is reproduced qualitatively by the Monte Carlo event generators PYTHIA 8, AMPT, and EPOS. However, the models overestimate the width in the low transverse-momentum region ($p_{\rm T} < ~ 3$ GeV/$c$). The per-trigger associated near-side yield increases with increasing multiplicity. Although this trend is also captured qualitatively by the considered event generators, the yield is mostly overestimated by the models in the considered kinematic range. The measurement of the shape and yield of the short-range correlation peak can help us understand the interplay between jet fragmentation and event activity, quantify the narrowing trend of the near-side peak as a function of transverse momentum and multiplicity selections in pp collisions, and search for final-state jet modification in small collision systems. \
2409.04501
Higher-order symmetry plane correlations in Pb$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV The correlations between event-by-event fluctuations of symmetry planes are measured in Pb$-$Pb collisions at a centre-of-mass energy per nucleon pair $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV recorded by the ALICE detector at the Large Hadron Collider. This analysis is conducted using the Gaussian Estimator technique, which is insensitive to biases from correlations between different flow amplitudes. The study presents, for the first time, the centrality dependence of correlations involving up to five different symmetry planes. The correlation strength varies depending on the harmonic order of the symmetry plane and the collision centrality. Comparisons with measurements from lower energies indicate no significant differences within uncertainties. Additionally, the results are compared with hydrodynamic model calculations. Although the model predictions provide a qualitative explanation of the experimental results, they overestimate the data for some observables. This is particularly true for correlators that are sensitive to the non-linear response of the medium to initial-state anisotropies in the collision system. As these new correlators provide unique information - independent of flow amplitudes - their usage in future model developments can further constrain the properties of the strongly-interacting matter created in ultrarelativistic heavy-ion collisions.
2409.04238
J/$ψ$-hadron correlations at midrapidity in pp collisions at $\sqrt{s}$ = 13 TeVWe report on the measurement of inclusive, non-prompt, and prompt J/$\psi$-hadron correlations by the ALICE Collaboration at the CERN Large Hadron Collider in pp collisions at a center-of-mass energy of 13 TeV. The correlations are studied at midrapidity ($|y| < ~ 0.9$) in the transverse momentum ranges $p_{\rm T} < ~ 40~\text{GeV}/c$ for the J/$\psi$ and $0.15 < ~ p_{\rm T} < ~ 10$ GeV/$c$ and $|\eta| < ~0.9$ for the associated hadrons. The measurement is based on minimum bias and high multiplicity data samples corresponding to integrated luminosities of $L_{\text{int}} = 34~\text{nb}^{-1}$ and $L_{\text{int}} = 6.9~\text{pb}^{-1}$, respectively. In addition, two more data samples are employed, requiring, on top of the minimum bias condition, a threshold on the tower energy of $E = 4$ and $9~\text{GeV}$ in the ALICE electromagnetic calorimeters, which correspond to integrated luminosities of $L_{\text{int}} = 0.9~\text{pb}^{-1}$ and $L_{\text{int}} = 8.4~\text{pb}^{-1}$, respectively. The results are presented as associated hadron yields per J/$\psi$ trigger as a function of the azimuthal angle difference between the associated hadrons and J/$\psi$ mesons. The integrated near-side and away-side correlated yields are also extracted as a function of the J/$\psi$ transverse momentum. The measurements are discussed in comparison to PYTHIA calculations.
2409.04364
Exploring nuclear structure with multiparticle azimuthal correlations at the LHC Understanding nuclear structure provides essential insights into the properties of atomic nuclei. In this paper, details of the nuclear structure of $^{\rm 129}$Xe, such as the quadrupole deformation and the nuclear diffuseness, are studied by extensive measurements of anisotropic-flow-related observables in Xe$-$Xe collisions at a center-of-mass energy per nucleon pair $\sqrt{s_{\rm NN}} = 5.44$ TeV with the ALICE detector at the LHC. The results are compared with those from Pb$-$Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV for a baseline, given that the $^{\rm 208}$Pb nucleus is not deformed. Furthermore, comprehensive comparisons are performed with a state-of-the-art hybrid model using IP-Glasma+MUSIC+UrQMD. It is found that among various IP-Glasma+MUSIC+UrQMD calculations with different values of nuclear parameters, the one using a nuclear diffuseness parameter of $a_0=0.492$ and a nuclear quadrupole deformation parameter of $\beta_2=0.207$ provides a better description of the presented flow measurements. These studies represent an important step towards a thorough exploration of the imaging power of nuclear collisions at ultrarelativistic energy and the search for the imprint of nuclear structure on various flow observables in heavy-ion collisions at the LHC. The findings demonstrate the potential of nuclear structure studies at the TeV energy scale and highlight that the LHC experiments can complement existing low-energy experiments on nuclear structure studies.
2409.04343
Particle production as a function of charged-particle flattenicity in pp collisions at $\sqrt{s}$ = 13 TeV This paper reports the first measurement of the transverse momentum ($p_{\mathrm{T}}$) spectra of primary charged pions, kaons, (anti)protons, and unidentified particles as a function of the charged-particle flattenicity in pp collisions at $\sqrt{s}=13$ TeV. Flattenicity is a novel event shape observable that is measured in the pseudorapidity intervals covered by the V0 detector, $2.8 < ~\eta < ~5.1$ and $-3.7 < ~\eta < ~-1.7$. According to QCD-inspired phenomenological models, it shows sensitivity to multiparton interactions and is less affected by biases towards larger $p_{\mathrm{T}}$ due to local multiplicity fluctuations in the V0 acceptance than multiplicity. The analysis is performed in minimum-bias (MB) as well as in high-multiplicity events up to $p_{\mathrm{T}}=20$ GeV/$c$. The event selection requires at least one charged particle produced in the pseudorapidity interval $|\eta| < ~1$. The measured $p_{\mathrm{T}}$ distributions, average $p_{\mathrm{T}}$, kaon-to-pion and proton-to-pion particle ratios, presented in this paper, are compared to model calculations using PYTHIA 8 based on color strings and EPOS LHC. The modification of the $p_{\mathrm{T}}$-spectral shapes in low-flattenicity events that have large event activity with respect to those measured in MB events develops a pronounced peak at intermediate $p_{\mathrm{T}}$ ($2 < ~p_{\mathrm{T}} < ~8$ GeV/$c$), and approaches the vicinity of unity at higher $p_{\mathrm{T}}$. The results are qualitatively described by PYTHIA, and they show different behavior than those measured as a function of charged-particle multiplicity based on the V0M estimator.
2407.20037
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Upcoming Conferences (Next Week)

12th Int Conf on Hard and Electromagnetic Probes of High-Energy Nuclear Collisions (Hard Probes 2024, HP2024)
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Jobs info

 

   Jobs info

ALICE Job - Postdoctoral researcher in the Detector R&D group for LHCb ( )
ALICE Job - Research Fellow / Software Engineer to be based at CERN, Geneva – The ALICE Experiment at the CERN LHC ( )
ALICE Job - Postdoctoral position at Universidade de São Paulo, Brazil ( )
ALICE Job - Three-year PhD position at the Laboratoire of the Physics of the two Infinities Irène Joliot-Curie (IJCLab), CNRS and Paris-Saclay University ( )
ALICE Job - Postdoctoral position on the cms tracker upgrade for HL-LHC ( )
See all jobs...

Diversity and Inclusivity in ALICE

The ALICE Collaboration embraces and values the diversity of its team members and colleagues. We are committed to fostering an inclusive environment for all people regardless of their nationality/culture, profession, age/generation, family situation and gender, as well as individual differences such as but not limited to ethnic origin, sexual orientation, belief, disability, or opinions provided that they are consistent with the Organization’s values.

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